Thank you for this! I'm actually working with a partner and kind of laid out these options for them. I added in a "view PDF" link to both the website AND the email thinking that was a nice compromise and a simplified the HTML as much as I could from the total mess it was but I think in this case option D is the real best choice for now.

I like the idea of investing more in the web experience and having the email be JUST text with a text only outline and a link to the webpage which also has the PDF link in it. While this approach is decidedly more googley off me, I just think it's the best compromise, but I think the person I'm working with may go for choice D. Long term I think detecting what the client has and presenting the right info for them is the smartest design, and this seems to be an issue that all those who distribute formatted text and image content must still struggle with to some extent when control over the client is non-existent.

It absolutely is an issue... at least with web you're told the browser version when they ask for the webpage.

With email, you have no way to know anything about how they receive it... it's "fire and forget". Makes the whole job of tailoring your content very difficult.

As a side-tip, if you want to study how other companies do it, you'll need to examine their emails with something that lets you look at the full raw source of the incoming email, multiple MIME parts and all. I don't recall offhand if Outlook really does that, or if it just shows you headers and the source of the MIME component it decided was your text.